#include<stdio.h>
int main(){
	int arr[10] = {0};
	int i = 0;
	int sum = 0;
	double avarage = 0.0;
	
	for( i=0; i<10; i++){
		scanf("%d " ,&arr[i]);	
	}
	int j = 0;
	for( j=0; j<10; j++){
		sum += arr[j];
	}
	avarage = sum / 10.0;
	printf("%lf\n" ,avarage);
	return 0;
} 
